A probe card assembly can be used to make temporary contact with a microelectronic device (e.g., a wafer comprising a plurality of dies) during testing. Typically, the probe card assembly is installed in a prober and an upper portion of the probe card assembly is docked to a test head. The device to be tested is placed on a chuck (or stage) and brought into contact with probes disposed on a lower surface of the probe card. A tester can then communicate with (e.g., provide test and control signals to and receive response signals from) the device to be tested through the test head and the probe car assembly.
As wafers have become larger, probe card assemblies have become correspondingly larger, with larger numbers of probes to make temporary connection by contacting dies on the wafer. In order to accommodate limited capabilities of testers, test circuitry can be included on the probe card to allow more dies to be tested in parallel. For example, the test circuitry on the probe card assembly can duplicate or split signals from the tester, allowing one tester channel to drive multiple dies. As another example, the test circuitry on the probe card assembly can include circuitry for checking response signals from multiple dies and providing summary fault information back to the tester. Other, more complex test circuitry can also be included on the probe card assembly.
During the process of developing a probe card assembly, it is often necessary to verify (e.g. debug) the probe card assembly to indentify and isolate problems. In some instances, problems cannot be detected until the probe card assembly has been installed in a prober (e.g., attached to the prober and/or docked to the test head). Unfortunately, once the probe card assembly has been installed into the prober, physical access to the probe card assembly to connect external test equipment (e.g., an oscilloscope probe, logic analyzer, or digital voltmeter) is difficult or impossible. Accordingly, it can be difficult to verify a probe card assembly.